The invention starts with a device to control and/or regulate the pressure level of at least one volume variable recipient of a pneumatic system, in particular a pneumatic system for a seat of a motor vehicle. In addition, the invention relates to a method to control and/or regulate the pressure level of such a system.
Pneumatic control and/or regulating circuits are used in a variety of technical applications. Thus, these types of systems are used in the area of motor vehicle technology in order to increase the seating comfort of vehicle passengers, for example. In this connection, volume variable recipients, such as air cushions or bladders that are made preferably of synthetic material are embedded in the vehicle seat, and these recipients can be acted upon by a working fluid via a corresponding device in order to thereby adapt the vehicle seat to individual desires with regard to hardness and shape.
A pneumatically controlled seat for a motor vehicle, which makes it possible for the driver to vary the pressure distribution in the seat, is known from U.S. Pat. No. 4,655,505, for example. This device includes a plurality of flexible, i.e., volume variable, air chambers that are integrated into the seat of the vehicle, which are connected to an air pump and a pressure sensor via a corresponding number of connecting means. Each connecting means features a valve, which can be triggered via electronic control means that evaluate the signal from the pressure sensor.
The combined, pneumatic and electrical circuit of this device allows defined pressures to build up in the individual air chambers of the seat via the plurality of valves. It is possible in this way to increase both the comfort of the seat as well as to intercept the vehicle's longitudinal or lateral accelerations.
In particular, the device from U.S. Pat. No. 4,655,505 allows the pressure in each individual air chamber to be varied continuously time-wise by the opening and closing of the control valves so that an optimized pressure distribution can be adjusted. As a result, it is also possible to generate a massage effect in the seat's air chambers via an oscillating change in the pressure conditions.
In order to achieve the desired pressure conditions or the desired variation in the pressure conditions of the individual air chambers of the seat, an expensive electronic control and regulating unit with corresponding electronics and at least one pressure sensor and a central computing unit is required in the system of U.S. Pat. No. 4,655,505.
A motor vehicle seat with inflatable cushions embedded in the upholstery is known from DE 35 05 088 C1. In the system in DE 35 05 088 C1, a pump generates compressed air and feeds it to a line in which a pressure volume reservoir is inserted. The pressure that is generated by the pump and fed to the storage reservoir via the line is adjacent to a pressure-regulating device on the inlet side, while the air cushions are deaerated on the outlet side via allocated magnetic valves, and thus the pressure in the cushions can be reduced. The compressed air is then fed to a magnetic valve, which is a part of a pressure-regulating device. Pressure is regulated via a regulating pressure return, wherein this pressure is adjacent to four magnetic valves on the inlet side. The magnetic valves are triggered by a distribution device, which features a sliding valve. The magnetic valve is triggered in the sliding valve's first position in such a way that the side cushions as well as a cushion in the area of the headrest is filled. Depending upon the position of the sliding valve, additional air cushions can be filled in the area of the seat backrests. The individual air cushions in the vehicle seat of DE 35 05 088 C1 can be deaerated into the atmosphere via the four magnetic valves.